Method for separating epitaxial layers and growth substrates, and semiconductor device using same

ABSTRACT

The present invention relates to a method for separating epitaxial layers and growth substrates, and to a semiconductor device using same. According to the present invention, a semiconductor device is provided which comprises a supporting substrate and a plurality of semiconductor layers provided on the supporting substrate, wherein the uppermost layer of the semiconductor layers has a surface of non-uniform roughness.

TECHNICAL FIELD

The present invention relates to a method for separating epitaxiallayers and growth substrates, and a semiconductor device using the same.

BACKGROUND ART

A light emitting diode generally refers to a PN junction diode in whicha p-type semiconductor and an n-type semiconductor are coupled.

In the light emitting diode (LED), when voltage is applied to the p-typeand n-type semiconductors coupled to each other, holes of the p-typesemiconductor are migrated toward the n-type semiconductor and electronsof the n-type semiconductor are migrated toward the p-type semiconductorsuch that the electrons and the holes are migrated into a PN junction.

The electrons moved into the PN junction are coupled to the holes whiledropping from the conduction band to the valence band. Then, energy isreleased in the form of light according to an energy gap between theconduction band and the valence band.

Such a light emitting diode is a semiconductor device capable ofemitting light and has various advantages such as eco-friendliness, lowvoltage, long lifetime, low price, and the like. Although such a lightemitting diode has been typically used in an indicating lamp or indisplaying numerals or other simple information, the light emittingdiode has recently been used in many different applications, such asdisplays, headlamps of vehicles, projectors, and the like, with thedevelopment of industrial technologies, in particular, informationdisplay technologies and semiconductor technologies.

However, since it is difficult to fabricate a homogenous substrate forgrowing a semiconductor layer of the light emitting diode, thesemiconductor layer is grown on a growth substrate having a similarcrystal structure by metal organic chemical vapor deposition (MOCVD),molecular beam epitaxy (MBE), and the like.

As the growth substrate, a sapphire substrate having a hexagonal systemis generally used. However, sapphire is a nonconductor of electricityand limits a structure of a light emitting diode to be formed thereon.

Therefore, various studies have been made to develop a technique forfabricating a vertical type light emitting diode by growing an epitaxiallayer for the semiconductor layer on a sapphire substrate or a similargrowth substrate, and separating the growth substrate.

To separate the growth substrate, the substrate may be removed bygrounding. However, the grounding technique for removing the growthsubstrate, that is, the sapphire substrate, is associated with longprocessing time and high cost.

Therefore, a laser lift-off (LLO) method, a stress lift-off (SLO)method, or a chemical lift-off (CLO) method is generally used toseparate the epitaxial layer from the growth substrate.

In the LLO method, an epitaxial layer is grown on a growth substrate, abonding substrate is bonded to the epitaxial layer, and a laser beam isemitted through the sapphire substrate so as to separate the epitaxiallayer from the growth substrate.

In the SLO method, a convex-concave pattern is formed on one surface ofa growth substrate, only a partial region of the growth substrate issubjected to passivation with an insulation film such that an epitaxiallayer can be grown only on the other region of the growth substrate, andthe epitaxial layer is thickly grown and then cooled, thereby allowingthe epitaxial layer to be separated by surface stress.

In the CLO method, a chemically vulnerable material is deposited in apredetermined pattern on one surface of a growth substrate, and then anepitaxial layer is grown and separated by electrochemically orchemically removing the chemically vulnerable material from the growthsubstrate.

Among these methods of separating the growth substrate, the LLO methodhas a problem in that properties of the epitaxial layer can bedeteriorated by heat generated from a laser beam. Further, the SLOmethod or the CLO method has a problem that a process becomescomplicated since a separate process for processing the surface of thegrowth substrate is performed before growing the epitaxial layer. Inaddition, the SLO method or the CLO method has a problem in massproduction since it takes more time to separate the epitaxial layer inpractice. Moreover, the application of the SLO method is not easy sincethe epitaxial layer must be grown thickly enough to be separated.

DISCLOSURE Technical Problem

The present invention is aimed at providing a method for easilyseparating an epitaxial layer from a growth substrate without affectingthe epitaxial layer.

The present invention is also aimed at providing a semiconductor devicefabricated using the method of separating an epitaxial layer from agrowth substrate.

Technical Solution

Embodiments of the present invention provide a method for separatingepitaxial layers from growth substrates, and a semiconductor deviceusing the same. In accordance with one aspect of the present invention,a semiconductor device includes: a support substrate; and a plurality ofsemiconductor layers formed on the support substrate, wherein anuppermost layer of the semiconductor layers has a surface of non-uniformroughness.

In accordance with another aspect of the present invention, a method ofseparating a growth substrate from an epitaxial layer includes:preparing a growth substrate; forming a convex-concave patterncomprising a plurality of convex portions and concave portions on onesurface of the growth substrate; epitaxially growing a sacrificial layeron the convex portions of the convex-concave pattern; forming aplurality of fine pores by performing electro chemical etching (ECE) onthe sacrificial layer; epitaxially growing a plurality of semiconductorlayers on the sacrificial layer; attaching a support substrate to thesemiconductor layers; and separating the growth substrate, wherein aplurality of voids is formed by merging or growing the fine pores withinthe sacrificial layer after the semiconductor layers are epitaxiallygrown on the sacrificial layer.

In accordance with a further aspect of the present invention, a methodof separating a growth substrate from an epitaxial layer includes:preparing a growth substrate; forming a convex-concave patterncomprising a plurality of convex portions and concave portions on onesurface of the growth substrate; epitaxially growing a sacrificial layeron the convex portions of the convex-concave pattern; forming a maskpattern on the sacrificial layer such that open regions can be formedcorresponding to the concave portions of the convex-concave pattern;epitaxially growing a plurality of semiconductor layers over the maskpattern from the sacrificial layer exposed through the open regions;etching at least a portion of the sacrificial layer exposed through theconcave portions and a portion of the semiconductor layer formed in theopen regions of the mask pattern by injecting an etching liquid foretching the sacrificial layer into the concave portions of theconvex-concave pattern; and separating the semiconductor layers from thegrowth substrate.

In accordance with yet another aspect of the present invention, a methodof separating a growth substrate from an epitaxial layer includes:preparing a growth substrate; growing a sacrificial layer on one surfaceof the growth substrate; forming a plurality of fine pores within thesacrificial layer; forming a plurality of cavities from the plurality offine pores; and separating the growth substrate using the plurality ofcavities.

Advantageous Effects

According to the present invention, a method of easily separating anepitaxial layer from a growth substrate without affecting the epitaxiallayer is provided.

In addition, a semiconductor device fabricated using the method ofseparating an epitaxial layer from a growth substrate is provided.

DESCRIPTION OF DRAWINGS

FIG. 1 is a conceptual view of a semiconductor device according to oneembodiment of the present invention.

FIG. 2 is a conceptual view of a semiconductor device according toanother embodiment of the present invention.

FIGS. 3 to 9 are cross-sectional views showing a method of fabricating asemiconductor device according to one embodiment of the presentinvention.

FIGS. 10 to 12 are cross-sectional views showing a method of fabricatinga semiconductor device according to another embodiment of the presentinvention.

FIG. 13 is a cross-sectional view showing a method of fabricating asemiconductor device according to a further embodiment of the presentinvention.

FIG. 14 is a cross-sectional view showing a method of fabricating asemiconductor device according to yet another embodiment of the presentinvention.

FIGS. 15 to 16 are cross-sectional views showing a method of fabricatinga semiconductor device according to yet another embodiment of thepresent invention.

FIG. 17 is a conceptual view of a semiconductor device according to yetanother embodiment of the present invention.

FIGS. 18 to 24 are cross-sectional views showing the method offabricating the semiconductor device of FIG. 17.

FIG. 25 is a cross-sectional view showing a method of fabricating asemiconductor device according to yet another embodiment of the presentinvention.

FIGS. 26 to 32 are cross-sectional views showing a method of separatinga growth substrate from a nitride semiconductor layer according to yetanother embodiment of the present invention.

FIG. 33 is a cross-sectional view of one example of a light emittingdiode including a nitride semiconductor layer separated by the method ofseparating a growth substrate from a nitride semiconductor layeraccording to yet another embodiment of the present invention.

FIG. 34 is a conceptual view of electro chemical etching (ECE).

FIGS. 35 and 36 are sectional views showing examples of fine poresformed by the ECE process.

FIGS. 37 to 38 are a perspective view and a cross-sectional view ofanother example of a light emitting diode including a nitridesemiconductor layer separated by the method of separating a growthsubstrate from a nitride semiconductor layer according to yet anotherembodiment of the present invention.

FIGS. 39 to 46 are cross-sectional views showing a method of separatinga growth substrate from a nitride semiconductor layer according to yetanother embodiment of the present invention.

FIG. 47 is a cross-sectional view of one example of a light emittingdiode including a nitride semiconductor layer separated by a method ofseparating a growth substrate from a nitride semiconductor layeraccording to yet another embodiment of the present invention.

FIG. 48 is a conceptual view of examples of stripe patterns formed onone surface of a growth substrate.

FIGS. 49 to 51 are a perspective view and cross-sectional views showinganother example of a light emitting diode including a nitridesemiconductor layer separated by a method of separating a growthsubstrate from a nitride semiconductor layer according to yet anotherembodiment of the present invention.

FIG. 52 is a cross-sectional view showing a method of separating agrowth substrate from a nitride semiconductor layer according to yetanother embodiment of the present invention.

FIGS. 53 to 58 are cross-sectional views showing a method of separatinga growth substrate from a nitride semiconductor layer according to yetanother embodiment of the present invention.

FIG. 59 is a cross-sectional view of one example of a light emittingdiode including a nitride semiconductor layer separated by a method ofseparating a growth substrate from a nitride semiconductor layeraccording to yet another embodiment of the present invention.

FIGS. 60 to 62 are a perspective view and cross-sectional views showinganother example of a light emitting diode including a semiconductorlayer separated by a method of separating a growth substrate from anitride semiconductor layer according to yet another embodiment of thepresent invention.

BEST MODE

Exemplary embodiments of the present invention will now be describedwith reference to the accompanying drawings.

FIG. 1 is a conceptual view of a semiconductor device according to oneembodiment of the present invention.

Referring to FIG. 1, a semiconductor device 100 according to oneembodiment of the present invention may include a support substrate 110,a bonding layer 120, and a plurality of semiconductor layers 130.

The support substrate 110 may be any kind of substrate capable ofsupporting the semiconductor layers 130.

The support substrate 110 may include a sapphire substrate, a glasssubstrate, a silicon carbide substrate, a GaN substrate or a siliconsubstrate; a conductive substrate formed of or including metallicmaterials; a circuit substrate such as a printed circuit board (PCB) andthe like; and a ceramic substrate containing ceramic.

The bonding layer 120 is formed on the support substrate 110 and servesto bond the support substrate 110 to the semiconductor layer 130.

The bonding layer 120 may be omitted. That is, the bonding layer 120 maybe omitted when the structures or materials of the support substrate 110can be sufficiently bonded to the semiconductor layer 130 without thebonding layer 120. For example, the bonding layer 120 may be omittedwhen the support substrate 110 is deposited or plated on thesemiconductor layers 130 or when the support substrate 110 ismechanically coupled to the semiconductor layers 130 by compression orthe like.

The semiconductor layers 130 may include a first type semiconductorlayer 132, an active layer 134, a second type semiconductor layer 136,and a sacrificial layer 138. When the semiconductor layer 130 includesat least the active layer 134, the semiconductor device 100 may be alight emitting diode.

The first type semiconductor layer 132 may be or include a group III-Ncompound semiconductor layer doped with first type impurities, forexample, p-type impurities, and may include, for example, an (Al, In,Ga)N group III nitride semiconductor layer. The first type semiconductorlayer 132 may be a GaN layer doped with p-type impurities, that is, ap-GaN layer. The first type semiconductor layer 132 may be composed of asingle layer or a plurality of layers. For example, the first typesemiconductor layer 132 may have a super-lattice structure.

The active layer 134 may be or include a group III-N semiconductorlayer, for example, an (Al, Ga, In)N semiconductor layer. The activelayer 134 may be composed of a single layer or a plurality of layersthat emit light having a certain wavelength. The active layer 134 mayhave a single quantum-well structure including one well layer (notshown), or a multi quantum-well structure wherein well layers (notshown) and barrier layers (not shown) are alternately stacked one aboveanother. At this time, each or both of the well layer (not shown) andthe barrier layer (not shown) may have the super-lattice structure.

The second type semiconductor layer 136 may be or include a group III-Ncompound semiconductor layer doped with second type impurities, forexample, n-type impurities, and may include, for example, an (Al, Ga,In)N group III nitride semiconductor layer. The second typesemiconductor layer 136 may be or include a GaN layer doped with n-typeimpurities, that is, an n-GaN layer. The second type semiconductor layer136 may be composed of a single layer or a plurality of layers. Forexample, the second type semiconductor layer 136 may have asuper-lattice structure when it is composed of a plurality of layers.

The sacrificial layer 138 may be or include a group III-N compoundsemiconductor layer doped with the second type impurities, for example,n-type impurities, and may include, for example, an (Al, Ga, In)N groupIII nitride semiconductor layer. Preferably, the sacrificial layer 138is or includes an n-GaN layer.

At this time, when the second type semiconductor layer 136 and thesacrificial layer 138 are formed of the same material, the second typesemiconductor layer 136 may be omitted, as needed.

The semiconductor layers 130 may further include a super-lattice layer(not shown) or an electron blocking layer (not shown).

The electron blocking layer (not shown) may be disposed between thefirst type semiconductor layer 132 and the active layer 134, and improverecombination efficiency between electrons and holes. The electronblocking layer (not shown) may include a material having a relativelywide band-gap. The electron blocking layer (not shown) may be formed ofor include an (Al, In, Ga)N group III nitride semiconductor, or may beor include a p-AlGaN layer doped with Mg.

The super-lattice layer (not shown) may be disposed between the activelayer 134 and the second type semiconductor layer 136, and may have astructure wherein the group III-N compound semiconductors, for example,(Al, Ga, In)N semiconductor layers, are stacked in a plurality oflayers, for example, a structure wherein InN layers and InGaN layers arealternately stacked one above another. The super-lattice layer (notshown) is formed prior to the active layer 124 and prevents dislocationsor defects from being transferred to the active layer 124, therebyimproving crystallinity of the active layer 134 by reducing dislocationor defect density in the active layer 124.

The sacrificial layer 138 may be disposed at an uppermost side of thesemiconductor layers 130. The sacrificial layer 138 is used inseparation of the semiconductor layers 130 from the growth substrate210, as described in the following methods of fabricating asemiconductor device.

The sacrificial layer 138 may have a rough surface 140 in a certainregion on one surface thereof.

The rough surface 140 may include at least one of a cut surface 142, aninner surface 144 of a cut void, and a plurality of V-shaped etchedgrooves 146. In FIG. 1, the rough surface 140 includes all of the cutsurface 142, the inner surface 144 of the cut void, and the plurality ofV-shaped etched grooves 146.

The cut surface 142 is a rough surface that can be formed in a certainregion on one surface of the sacrificial layer 138, and may be the samesurface as the surface when the sacrificial layer 138 is broken bystress in a horizontal direction (i.e. a direction parallel to thesurface of the support substrate 110).

The cut surface 142 may be a surface formed and cut by applying stressto the sacrificial layer 138 in a region without a formation of a voidor an etching with an etching liquid, as described in the followingmethods of fabricating a semiconductor device.

The inner surface 144 of the cut void may be a surface formed when avoid having a circular shape, an elliptical shape or the like is cut toexpose an inner surface thereof.

The inner surface 144 of the cut void may be a surface formed when thevoid formed in the sacrificial layer 138 is divided when the sacrificiallayer 138 is cut or etched, as described in the following methods offabricating a semiconductor device.

The plurality of V-shaped etched grooves 146 may be a surface formedwhen the sacrificial layer 138 is exposed to the etching liquid andetched to have a V-shape.

The plurality of V-shaped etched grooves 146 may be a surface exposedwhen the sacrificial layer 138 is etched with the etching liquid suchthat a certain region of the sacrificial layer 138 exposed through aconcave portion 222 of the growth substrate 210 is first etched to havea V-shape, as described in the following methods of fabricating asemiconductor device.

Therefore, the semiconductor device 100 according to the embodiment ofthe invention includes the support substrate 110 and the semiconductorlayers 130, in which the uppermost layer of the semiconductor layers130, i.e. the sacrificial layer 138, has a rough surface 140 ofnon-uniform roughness, and the rough surface 140 includes the cutsurface 142 of the sacrificial layer 138 and the inner surface 144 ofthe cut void or the plurality of V-shaped etched grooves 146. When thesemiconductor device 100 is a light emitting diode, light emitted fromthe active layer 134 of the semiconductor layers 130 can be easilyextracted through the uppermost layer, thereby improving luminousefficiency.

FIG. 2 is a conceptual view of a semiconductor device according toanother embodiment of the present invention.

Referring to FIG. 2, a semiconductor device 200 according to thisembodiment may include a support substrate 210, a bonding layer 220, anda plurality of semiconductor layers 230.

The semiconductor layers 230 may include a first type semiconductorlayer 232, an active layer 234, a second type semiconductor layer 236,and a sacrificial layer 238.

The semiconductor device 200 according to this embodiment of theinvention has the same configuration as the semiconductor device 100described in FIG. 1 except for the sacrificial layer 238. Therefore,repetitive descriptions of the support substrate 210, the bonding layer220 and the semiconductor layer 230 including the first typesemiconductor layer 232, the active layer 234 and the second typesemiconductor layer 236 will be omitted.

The elements of the support substrate 210, the bonding layer 220 and thesemiconductor layer 230 including the first type semiconductor layer232, the active layer 234 and the second type semiconductor layer 236could be understood by referring to the support substrate 110, thebonding layer 120 and the semiconductor layers 130 including the firsttype semiconductor layer 132, the active layer 134 and the second typesemiconductor layer 136.

In this embodiment, the sacrificial layer 238, i.e. the uppermost layerof the semiconductor layer 230, may include at least one open region 240to expose another semiconductor layer, for example, the second typesemiconductor layer 236, under the sacrificial layer 238.

The open region 240 may be formed by partially patterning thesacrificial layer 238 and may expose the layer under the sacrificiallayer 238. As described in the following methods of fabricating asemiconductor device, the open region 240 may be formed by forming thesacrificial layer 238 by epitaxial growth on respective convex portions324 of a growth substrate 310 so as not to be merged into one layer suchthat the layers grown on the neighboring convex portions 324 do notcontact each other.

FIGS. 3 to 9 are cross-sectional views showing a method of fabricating asemiconductor device according to one embodiment of the presentinvention.

Referring to FIG. 3, a growth substrate 310 is first prepared.

The growth substrate 310 may be any substrate on which the semiconductorlayer can be formed by epitaxial growth. The growth substrate 310 may bea sapphire substrate, a glass substrate, a silicon carbide (SiC)substrate, a silicon (Si) substrate, or the like. Preferably, the growthsubstrate 310 may be a sapphire substrate.

A convex-concave pattern 320 having concave portions 322 and convexportions 324 is formed on one surface of the growth substrate 310.

The concave portions 322 have a width and depth of several μm or less,and the convex portions 324 have a width and height of several μm orless.

Here, although FIG. 3 shows the plurality of concave portions 322 andthe plurality of convex portions 324, it should be understood that thepresent invention is not limited thereto. Alternatively, theconvex-concave pattern 320 may include a plurality of convex portions324 and a single concave portion 322 surrounding the respective convexportions 324 (that is, in a structure wherein the convex portions 324protrude from one surface). The concave portions 322 and the convexportions 324 are alternately provided in the form of a stripe pattern.Here, the concave portions 322 may be connected to one another to allowan etching liquid to be injected into the concave portions 322.

The concave portion 322 may be formed in a trapezoidal groove shape, across-section of which has a narrow lower side and a wide upper side.

The convex-concave pattern 320 may be formed by etching the concaveportions 322.

Referring to FIG. 4, a growth control layer 330 is formed in the concaveportions 322 of the growth substrate 310.

The growth control layer 330 prevents the semiconductor layers 130 fromgrowing in the concave portions 322 of the convex-concave pattern 320.

The growth control layer 330 may be formed only to an extent of coveringbottom surfaces of the concave portions 322. This is because epitaxialgrowth of the semiconductor layers 130 described below is notsubstantially performed on a lateral surface between the concaveportions 322 and the convex portions 324.

Referring to FIG. 5, the sacrificial layer 138 is formed as one of thesemiconductor layers 130 on the growth substrate 310 by epitaxialgrowth.

The sacrificial layer 138 may include n-GaN, and be formed by epitaxialgrowth using an MOCVD system or other chemical vapor deposition systems.

The sacrificial layer 138 can be used to appropriately adjust the dopingconcentration of n-type impurities depending upon processing conditionsof electro chemical etching (ECE) described below, i.e. applied voltage,processing time, or processing temperature. Through adjustment of then-type impurities and the processing conditions of the ECE process, finepores 331 described below are adjusted, thereby enabling adjustment ofthe size, number or forming positions of the voids 340.

The sacrificial layer 138 may have a thickness of not more than 3 μm,and preferably a thickness of not more than 2 μm.

Referring to FIG. 6, the ECE process is applied to the sacrificial layer138 such that the plurality of fine pores 331 can be formed to apredetermined depth from the surface of the sacrificial layer 138.

In the ECE process, the growth substrate 310 having the sacrificiallayer 138 is dipped in an etching liquid, for example, an oxalic acidsolution, and voltage is applied thereto. At this time, the ECE processcan adjust the depth of the fine pores 331 by controlling the appliedvoltage, the processing time, or the temperature of the etching liquid.

The fine pores 331 are formed to have a depth of 1 μm when thesacrificial layer 138 is formed to a thickness of 2 μm. It should beunderstood that the depth of the fine pores 331 can be adjusted, asneeded.

Referring to FIG. 7, the semiconductor layers, that is, the second typesemiconductor layer 136, the active layer 134 and the first typesemiconductor layer 132, are sequentially formed on the sacrificiallayer 138.

The first type semiconductor layer 132, the active layer 134 and thesecond type semiconductor layer 136 are formed by epitaxial growth usingan MOCVD system or other CVD systems.

That is, the semiconductor layers may be formed through regrowth afterforming the fine pores 331 in the sacrificial layer 138. Although notshown in detail, the same layer as the sacrificial layer 138, i.e. anadditional sacrificial layer (not shown), may be further formed on thesacrificial layer 138 by epitaxial growth, and then the semiconductorlayers including the first type semiconductor layer 132, the activelayer 134 and the second type semiconductor layer 136 are formed byepitaxial growth.

Since the semiconductor layers including such an additional sacrificiallayer (not shown) are formed by epitaxial growth, the plurality of voids340 are formed from the fine pores 331.

Each of the voids 340 may be formed by merging the plurality of finepores 331 into one, or by growing a single fine pore 331.

When the semiconductor layers including such an additional sacrificiallayer (not shown) are formed by epitaxial growth, the size, the positionand the number of voids 340 are controlled by adjusting the growthtemperature for epitaxial growth or the kind or flow rate of injectedgas.

Referring to FIG. 8, the support substrate 110 is attached to thesemiconductor layers 130.

The support substrate 110 and the semiconductor layers 130 may beattached by forming the bonding layer 120 between the support substrate110 and the semiconductor layers 130.

The bonding layer 120 may include a conductive material.

The bonding layer 120 may be omitted. The bonding layer 120 is omittedwhen the support substrate 110 is thermally or mechanically compressedand attached to the semiconductor layers 130. Alternatively, the bondinglayer 120 is omitted when the support substrate 110 is formed on thesemiconductor layers by a deposition or plating such that the supportsubstrate 110 can be directly attached to the semiconductor layers 130.

Referring to FIG. 9, the growth substrate 310 is separated from thesupport substrate 110 having the semiconductor layers 130.

Separation of the growth substrate 310 may be performed by using thesacrificial layer 138.

That is, the growth substrate 310 may be separated by applying stress tothe sacrificial layer 138 and breaking the sacrificial layer 138.

Since the voids 340 are formed within the sacrificial layer 138, thesacrificial layer 138 can be easily broken. That is, when stress isapplied to the sacrificial layer 138, stress is concentrated on thevoids 340 such that regions between the voids 340 are broken, therebybreaking the sacrificial layer 138.

Therefore, as shown in FIG. 9, the sacrificial layer 138 is separatedwhile forming, on a surface of the sacrificial layer 138, the cutsurface 142 generated when the sacrificial layer 18 is broken or theinner surface 144 of the cut void generated when the voids 340 arebroken.

The separated growth substrate 310 may be reused after a cleaningprocess for removing a part of the sacrificial layer 138 remaining onthe surface thereof.

FIGS. 10 to 12 are cross-sectional views showing a method of fabricatinga semiconductor device according to another embodiment of the presentinvention.

Referring to FIG. 10 and FIG. 11, the method of fabricating asemiconductor device according to this embodiment includes the sameprocesses as those of the fabrication method described with reference toFIG. 3 to FIG. 9, except for the process of separating the growthsubstrate 310. Therefore, repetitive descriptions thereof will beomitted.

After attaching the support substrate 110 to the semiconductor layers130 including the sacrificial layer 138 formed therein with the voids340 via the bonding layer 120, the etching liquid is injected into theconcave portions 322 of the growth substrate 310 to etch the sacrificiallayer 138.

The etching liquid may include any etching liquid capable of selectivelyetching the sacrificial layer 138, which may an etching liquidcontaining sodium hydroxide, hydrogen peroxide and pure water, anetching liquid containing potassium hydroxide and pure water, or anetching liquid containing sulfuric acid.

When the sacrificial layer 138 is continuously etched using the etchingliquid, as shown in FIG. 11, a plurality of V-shaped etched grooves 146may be formed on the sacrificial layer 138. In addition, the etchingliquid etches the sacrificial layer 138 in a lateral direction along thevoids 340, thereby etching and separating the sacrificial layer 138.

At this time, a certain region 350 of the sacrificial layer 138 mayremain instead of being separated, since no etching liquid penetratesthe sacrificial layer 138. Of course, the certain region 350 may beremoved by controlling the etching process.

Referring to FIG. 12, the growth substrate 310 is separated from thesemiconductor layers 130 including the sacrificial layer 138 by etchingthe sacrificial layer 138 with the etching liquid or applying stress tothe sacrificial layer 138 after etching the sacrificial layer 138 withthe etching liquid.

In the semiconductor device fabricated by the method according to thisembodiment, the sacrificial layer 138 on the support substrate 110includes the cut surface 142, the inner surface 144 of the cut void, orthe plurality of V-shaped etched grooves 146, as shown in FIG. 12.

FIG. 13 is a cross-sectional view showing a method of fabricating asemiconductor device according to yet another embodiment of the presentinvention.

Referring to FIG. 13, the method of fabricating a semiconductor deviceaccording to this embodiment includes substantially the same process asthe fabrication method described with reference to FIG. 3 to FIG. 9,except that the convex-concave pattern 320 of the growth substrate 310has a different shape and thus there is no need for the growth controllayer 330. Therefore, repetitive descriptions thereof will be omitted.

That is, according to this embodiment, the convex-concave pattern 320 isformed in the process of preparing the growth substrate 310. The concaveportions 326 are formed as grooves having V-shaped cross-sectionsinstead of the trapezoidal cross section having a narrow bottom side anda wide top side.

Here, the concave portions 326 may be formed by etching the growthsubstrate 310 with an etching liquid, for example, an etching liquidcontaining sulfuric acid or phosphoric acid.

When the growth substrate 310 is a sapphire substrate, the concaveportions 326 may be formed as V-shaped grooves by etching the c-planeand the r-plane of the sapphire substrate using the etching liquid.

FIG. 14 is a cross-sectional view showing a method of fabricating asemiconductor device according to yet another embodiment of the presentinvention.

Referring to FIG. 14, the method of fabricating a semiconductor deviceaccording to this embodiment of the invention includes substantially thesame process as the fabrication method described with reference to FIG.10 to FIG. 12, except that the convex-concave pattern 320 of the growthsubstrate 310 has a different shape and thus there is no need for thegrowth control layer 330. Therefore, repetitive descriptions thereofwill be omitted.

According to this embodiment, the convex-concave pattern 320 is the sameas the convex-concave pattern 320 including the concave portions 326 andthe convex portions 324 described with reference to FIG. 13, and thusrepetitive descriptions thereof will be omitted.

FIGS. 15 to 16 are cross-sectional views showing a method of fabricatinga semiconductor device according to yet another embodiment of thepresent invention. Here, this method will be described based on themethod of fabricating the semiconductor device 200 described withreference to FIG. 2.

Referring to FIG. 15, the method of fabricating a semiconductor deviceaccording to this embodiment includes preparing a growth substrate 310as described with reference to FIG. 3 and FIG. 4, and forming aconvex-concave pattern 320 including a plurality of concave portions 322and convex portions 324 on one surface of the growth substrate 310. Theconvex-concave pattern 320 may include convex portions 324 and concaveportions 326 formed as V-shaped grooves as described with reference toFIG. 13 or FIG. 14.

Then, like the sacrificial layer 138 described in FIG. 5, a sacrificiallayer 238 may be formed on the growth substrate 310 by epitaxial growth.

The sacrificial layer 138 described in FIG. 5 is formed by merging manyseed layers (not shown) respectively grown on the plurality of convexportion 324 with each other, whereas the sacrificial layer 238 in thisembodiment is formed to have a plurality of open regions 260 by stoppingepitaxial growth before many seed layers (not shown) respectively grownin the convex portions 324 are merged with each other.

Although not shown, the sacrificial layer 238 having the plurality ofopen regions 260 may also be formed by forming the sacrificial layer 138by the process described with reference to FIG. 5, followed by partiallypatterning the sacrificial layer 1348 through an etching process or thelike.

After forming the sacrificial layer 238, a first type semiconductorlayer 232, an active layer 234, a second type semiconductor layer 236, abonding layer 220 and a support substrate 210 are formed and attachedusing the same processes described with reference to FIG. 6 through FIG.8 for forming and attaching the first type semiconductor layer 132, theactive layer 134, the second type semiconductor layer 136, the bondinglayer 120 and the support substrate 110. Here, repetitive descriptionswill be omitted.

Referring to FIG. 16, after the support substrate 210 is attached to thesemiconductor layer 230, the growth substrate 310 is separated by thesame method as the method described with reference to FIG. 9, i.e. byapplying stress to the sacrificial layer 238, thereby forming thesemiconductor device 200.

At this time, on a surface of the sacrificial layer 238, a cut surface242 and an inner surface 244 of a cut void are formed using the samemethod as the method of forming the cut surface 142 and the innersurface 144 of the cut void described with reference to FIG. 9.

In addition, the sacrificial layer 238 may include a plurality of openregions 360 exposing the semiconductor layer under the sacrificial layer238, for example, the surface of the second type semiconductor layer236. At this time, the open regions 360 may be formed in regionscorresponding to the concave portions 322 of the growth substrate 310,respectively.

FIG. 17 is a conceptual view of a semiconductor device according to yetanother embodiment of the present invention.

Referring to FIG. 17, a semiconductor device 100 according to oneembodiment of the present invention may include a support substrate 110,a bonding layer 120, and a plurality of semiconductor layers 430.

The support substrate 110 and the bonding layer 120 are the same asthose of the semiconductor device 100 shown in FIG. 1 and FIG. 2, andthus repetitive descriptions thereof will be omitted. In addition,components of the semiconductor layer 430 are the same as those of thesemiconductor device 100 shown in FIG. 1 and FIG. 2 except for anuppermost layer 438, and thus repetitive descriptions thereof will beomitted.

The uppermost layer 438 is formed on an uppermost side of thesemiconductor layers 430.

In addition, the uppermost layer 438 may include V-shaped etched grooves438 a or unmerged grooves 438 b on the surface thereof.

The V-shaped etched grooves 438 a may be formed by partially etching theuppermost layer 438 when the semiconductor layers 430 including theuppermost layer 438 are separated from the growth substrate 110, asdescribed in the following methods of fabricating a semiconductor deviceaccording to one embodiment of the invention. Further, the unmergedgrooves 438 b may be formed by controlling epitaxial growth when theuppermost layer 438 is formed by epitaxial growth. In the followingmethod, the V-shaped etched grooves 438 a or the unmerged grooves 438 bwill be described in more detail.

FIGS. 18 to 24 are cross-sectional views showing a method of fabricatingthe semiconductor device of FIG. 17.

Referring to FIG. 18, first, a growth substrate 310 is prepared.

The growth substrate 310 may be any substrate on which the semiconductorlayer can be formed by epitaxial growth. The growth substrate 310 mayinclude a sapphire substrate, a glass substrate, a silicon carbide (SiC)substrate, or a silicon (Si) substrate. Preferably, the growth substrate310 is a sapphire substrate.

A convex-concave pattern 320 including concave portions 322 and convexportions 324 is formed on one surface of the growth substrate 310.

The concave portions 322 have a width and depth of several μm or less,and the convex portions 324 have a width and height of several μm orless.

Here, although FIG. 18 shows the plurality of concave portions 322 andthe plurality of convex portions 324, it should be understood that thepresent invention is not limited thereto. Alternatively, theconvex-concave pattern 320 may include a plurality of convex portions324 and a single concave portion 322 surrounding the respective convexportions 324 (i.e. in a structure wherein the convex portions 324protrude from one surface). The concave portions 322 and the convexportions 324 are alternately provided in the form of a stripe pattern.Here, the concave portions 322 may be connected to one another to allowan etching liquid to be injected into the concave portions 322.

The concave portion 322 may be formed in a trapezoidal groove shape, across-section of which has a narrow lower side and a wide upper side.

The convex-concave pattern 320 may be formed by etching the concaveportions 322.

Referring to FIG. 19, a growth control layer 330 is formed in theconcave portions 322 of the growth substrate 310.

The growth control layer 330 prevents the semiconductor layers fromgrowing in the concave portions 322 of the convex-concave pattern 320.

The growth control layer 330 may be formed of an insulation film such assilicon oxide (SiO₂), silicon nitride (SiN), etc. In addition, thegrowth control layer 330 may be formed of the same material as that ofthe mask pattern.

The growth control layer 330 may be formed only to an extent of coveringbottom surfaces of the concave portions 322. This is because epitaxialgrowth of the semiconductor layers 130 described below is notsubstantially performed on a lateral surface between the concaveportions 322 and the convex portions 324.

Then, the sacrificial layer 440 is formed on the growth substrate 310 byepitaxial growth.

The sacrificial layer 140 may include a semiconductor layer includingGaN, for example, n-GaN, and be formed by epitaxial growth using anMOCVD system or other chemical vapor deposition systems. Here, thesacrificial layer 440 may be realized by a μ-GaN layer doped with noimpurity, like the uppermost layer 438.

Referring to FIG. 20, a mask pattern 450 may be formed on thesacrificial layer 440.

The mask pattern 450 may be formed of a material having a higher etchselectivity than the sacrificial layer 440, and may be formed of aninsulation layer, such as silicon oxide, silicon nitride and the like.

The mask pattern 450 may include open regions 452 that expose thesacrificial layer 440 under the mask pattern 450.

The open regions 452 may be placed in regions corresponding to theconcave portions 322 of the convex-concave pattern 320.

Referring to FIG. 21, the mask pattern 450 is formed on the sacrificiallayer 440, and then the uppermost layer 438 is grown from the surface ofthe sacrificial layer 440 under the mask pattern 450 and exposed throughthe open regions 452.

At this time, the uppermost layer 438 may be epitaxially grown until theepitaxial layers are epitaxially grown from the neighboring open regions452 and completely merged into one layer.

As shown in FIG. 21, the uppermost layer 438 may be epitaxially grownover the mask pattern 450 from the neighboring open regions 452 suchthat the grown epitaxial layers are not completely merged with oneanother. That is, the uppermost layer 438 is epitaxially grown over themask pattern 450 from the neighboring open regions 452 within theuppermost layer 438 such that the grown epitaxial layers are notcompletely merged so as to have the unmerged groove 438 b.

Referring to FIG. 22, the semiconductor layers, i.e. a second typesemiconductor layer 436, an active layer 434 and a first typesemiconductor layer 432 are sequentially formed after forming theuppermost layer 438.

The first type semiconductor layer 432, the active layer 434 and thesecond type semiconductor layer 436 may be formed by epitaxial growthusing an MOCVD system or other chemical vapor deposition systems.

After epitaxial growth of the semiconductor layers 430 is completed, thesupport substrate 110 is attached to the semiconductor layers 130.

At this time, the support substrate 110 and the semiconductor layers 430may be attached by forming a bonding layer 120 between the supportsubstrate 110 and the semiconductor layers 430 and providing aconnection between the support substrate and the semiconductor layers430.

The bonding layer 120 may include a conductive material.

The bonding layer 120 may be omitted. The bonding layer 120 is omittedwhen the support substrate 110 is thermally or mechanically compressedand attached to the semiconductor layers 130. Alternatively, the bondinglayer 120 is omitted when the support substrate 110 is formed on thesemiconductor layers 130 by a deposition or plating such that thesupport substrate 110 can be directly attached to the semiconductorlayers 130.

Referring to FIG. 23, the sacrificial layer 440 is etched by injectingan etching liquid into the concave portions 322 of the growth substrate310.

At this time, the etching liquid etches the semiconductor layer 430including the sacrificial layer 440 but does not etch the mask pattern450.

The etching liquid partially etches the sacrificial layer 440 exposedthrough the concave portions 322 of the convex-concave pattern 320, andetches a portion of the semiconductor layers 430, i.e. a portion of theuppermost layer 438 provided within the open regions 452 of the maskpattern 450.

When the uppermost layer 438 is sufficiently etched by the etchingliquid, portions of the uppermost layer 438 provided not only in theopen regions 452 of the mask pattern 450 but also in the open regions452 of the mask pattern 450 are etched, whereby V-shaped etched grooves438 a can be formed on the surface of the uppermost layer 438 when thesemiconductor layers 430 is separated from the growth substrate 210. Inaddition, etching of the uppermost layer 438 using the etching liquid isproperly controlled such that the V-shaped etched grooves 438 a are notformed on the surface of the uppermost layer 438. In addition,protrusions (not shown) may be formed in regions corresponding to theV-shaped etched grooves 438 a, unlike those shown in FIG. 17 or FIG. 23.That is, the portions of the uppermost layer 438 within the open regions452 may be not completely etched, whereby the protrusions (not shown)can be formed on the surface of the uppermost layer 438.

Referring to FIG. 24, the mask pattern 450 is removed to separate thegrowth substrate 210 from the support substrate 110 having thesemiconductor layers 430 formed thereon, thereby forming thesemiconductor device 100 as described with reference to FIG. 1.

The mask pattern 450 may be removed by various methods, for example, amethod using a buffered oxide etchant (BOE), HF, or a similar liquefiedor gaseous etching material including fluorine (F). When the growthcontrol layer 330 is formed of the same material as the mask pattern450, the growth control layer may be removed by the same material orprocess of removing the mask pattern 450.

Although not shown, mesa etching for partially exposing a surface of thefirst semiconductor layer 432 may be performed by partially etching theuppermost layer 438, the second semiconductor layer 436 and the activelayer 434, and then a first electrode (not shown) is formed on thepartially exposed surface of the first semiconductor layer 432, followedby forming a transparent electrode layer (not shown) and a secondelectrode (not shown) on the uppermost layer 438. Thus, it is possibleto fabricate a light emitting diode using the semiconductor device 100.

FIG. 25 is a cross-sectional view showing a method of fabricating asemiconductor device according to yet another embodiment of the presentinvention.

Referring to FIG. 25, the method of fabricating a semiconductor deviceaccording to this embodiment of the invention includes the sameprocesses as those of the fabrication method described with reference toFIG. 18 to FIG. 24, except that the convex-concave pattern 320 of thegrowth substrate 310 has a different shape and thus there is no need forthe growth control layer 330 (see FIG. 24). Thus, repetitivedescriptions thereof will be omitted.

That is, in this embodiment, the convex-concave pattern 320 is formed inthe process of preparing the growth substrate 310, in which concaveportions 326 are formed in a groove shape having a V-shaped crosssection, instead of the trapezoidal cross section having a narrow bottomside and a wide top side.

Here, the concave portions 326 may be formed by etching the growthsubstrate 310 with an etching liquid, for example, an etching liquidincluding sulfuric acid or phosphoric acid.

When the growth substrate 310 is a sapphire substrate, the concaveportions 326 may be formed as V-shaped grooves when the etching liquidetches c-surface and r-surface of the sapphire substrate.

FIGS. 26 to 32 are cross-sectional views showing a method of separatinga growth substrate from a nitride semiconductor layer according to yetanother embodiment of the present invention.

FIG. 33 is a cross-sectional view of one example of a light emittingdiode including a nitride semiconductor layer separated by the method ofseparating a growth substrate from a nitride semiconductor layeraccording to this embodiment of the invention.

FIG. 34 is a conceptual view of electro chemical etching (ECE).

FIGS. 35 and 36 are sectional views showing examples of fine poresformed by the ECE process.

Referring to FIG. 26, in the method of separating a growth substratefrom a nitride semiconductor layer according to this embodiment, first,a growth substrate 510 is prepared.

The growth substrate 510 may include a sapphire substrate, a GaNsubstrate, a glass substrate, a silicon carbide (SiC) substrate, asilicon (Si) substrate, or the like. Preferably, the growth substrate510 is a sapphire substrate or a GaN substrate.

After placing the growth substrate 510 in a chamber of an epitaxialgrowth system such as an MOCVD system, a sacrificial layer 520 is grownon the growth substrate 510. The sacrificial layer 520 may include GaNdoped with impurities, preferably n-GaN highly doped with n-typeimpurities.

Referring to FIG. 27, a plurality of fine pores 531 are formed in thesacrificial layer 520.

The fine pores 531 may be formed by the ECE process.

In the ECE process as shown in FIG. 8, the growth substrate 510 havingthe sacrificial layer 520 formed thereon is dipped into an ECE solution512, and then the fine pores 531 are formed by an electric fieldgenerated upon voltage application.

The ECE solution 512 may be an electrolyte solution, and preferably anelectrolyte solution including oxalic acid, HF or NaOH.

In the ECE process, a negative electrode 514 is placed in the ECEsolution 512. The negative electrode 514 is separated by a predetermineddistance from the sacrificial layer 520 when the sacrificial layer 520is dipped into the ECE solution 512.

In the ECE process, with the sacrificial layer 520 dipped into the ECEsolution 512, a (+) power terminal is applied to the sacrificial layer520 and a (−) power terminal is applied to the negative electrode 514.

The fine pores 531 may be formed to a predetermined depth from thesurface of the sacrificial layer 520 inside the sacrificial layer 520.The depth or the diameter of the fine pores 531 may be adjusted bycontrolling the applied voltage, the processing time, the dopingconcentration of the sacrificial layer 520, or the temperature of theECE solution.

As shown in FIG. 33 and FIG. 34, the fine pores 531 may include at leasttwo regions, i.e. first fine pores 532 and second fine pores 534. Thesecond fine pores 534 may have a larger diameter than the first finepores 532.

The fine pores 531 are formed to have the first fine pores 532 and thesecond fine pores 53 such that a region close to the surface of thesacrificial layer 520, i.e. the first fine pores 532, can be formed withfine pores having a small diameter and the interior of the sacrificiallayer 520, i.e. the second fine pores 534, can be formed with fine poreshaving a large diameter, thereby reducing damage to the nitridesemiconductor layer 550 when the nitride semiconductor layer 550 isgrown again on the sacrificial layer 520, while forming large cavities560 inside the sacrificial layer 520 or increasing the number ofcavities 560.

As shown in FIG. 34, in the process of forming the fine pores 531, thefine pores 531 are formed by applying voltage of at least two levelsafter the sacrificial layer 520 is dipped into the ECE solution, wherebythe first fine pores 532 and the second fine pores 534 can be formed.

That is, the first fine pores 532 are first formed by a first voltageand the second fine pores 534 are formed by a second voltage higher thanthe first voltage.

Therefore, in the process of forming the fine pores 531 as shown in FIG.34, at least two different voltages are applied to form the fine pores531.

As shown in FIG. 35, in the process of forming the fine pores 531, whenthe sacrificial layer 520 is formed, the first fine pores 532 and thesecond fine pores 534 are formed by forming a first sacrificial layer522 and a second sacrificial layer 524 having different impurityconcentrations, dipping the growth substrate 510 formed with the firstsacrificial layer 522 and the second sacrificial layer 524 into the ECEsolution, and applying voltage thereto. Here, the first sacrificiallayer 522 may be doped with a higher concentration of impurities thanthe second sacrificial layer 524.

Thus, in the process of forming the fine pores 531 as shown in FIG. 35,when the sacrificial layer 520 is formed, at least two sacrificiallayers 520 having different impurity concentrations are formed and thensubjected to the ECE process.

In the process of forming the fine pores 531 as shown in FIG. 35, theECE process is realized by applying voltage of one level. However,voltage of two or more levels may be applied and the size of first finepores 532 may be increased.

Referring to FIG. 28, an insulation pattern 540 is formed on thesacrificial layer 520 having the fine pores.

The insulation pattern 540 may include an insulation material, such assilicon oxide or silicon nitride.

The insulation pattern 540 may include open regions in the form of astripe or mesh pattern.

The width, thickness, shape, and the like of the insulation pattern 540may be determined in consideration of dicing or light extractionefficiency when the light emitting diode is formed using the nitridesemiconductor layer separated by the method of separating a growthsubstrate from a nitride semiconductor layer according to one embodimentof the present invention.

The insulation pattern 540 may have a thickness of 240 nm.

Referring to FIG. 29, a plurality of nitride semiconductor layers 550are formed on the sacrificial layer 520 formed with the insulationpattern 540.

The plurality of nitride semiconductor layers 550 may be formed throughregrowth by placing the growth substrate 510 again into the chamber ofthe epitaxial growth system such as a MOCVD system.

That is, the plurality of nitride semiconductor layers 550 may beepitaxially grown from the surface of the sacrificial layer 520 exposedthrough the open regions of the insulation pattern 540.

Here, the fine pores 531 of the sacrificial layer 520 may be formed asthe plurality of cavities 560 when the plurality of nitridesemiconductor layers 550 is formed by epitaxial growth.

The plurality of cavities 560 may be formed by merging the plurality offine pores 531 into one, or expanding one fine pore 531.

When the plurality of nitride semiconductor layers 550 are epitaxiallygrown, the size, position, number, etc. of cavities 560 may be adjustedby controlling the temperature for epitaxial growth, or the kind andflow rate of injected gas.

The cavities 560 are generally formed in an upper region of thesacrificial layer 520 (here, the upper region of the sacrificial layer520 refers to a region close to an interface bordering the plurality ofnitride semiconductor layers 550).

The cavities 560 may be formed to be larger in a distant region of thesacrificial layer 520 from the plurality of nitride semiconductor layers550 than a close region, and may be formed to become larger withincreasing distance from the plurality of nitride semiconductor layers550.

FIG. 29 shows that the plurality of nitride semiconductor layers 550includes a first nitride semiconductor layer 552 and a second nitridesemiconductor layer 554, without being limited thereto. Alternatively,the nitride semiconductor layer may be a single layer, or may includethree or more layers.

The first nitride semiconductor layer 552 may be a buffer layer and thesecond nitride semiconductor layer 554 may be a semiconductor layerincluding at least an active layer.

That is, the first nitride semiconductor layer 552 may be an n-GaN layerdoped with n-type impurities or a μ-GaN layer doped with no impurity.

The second nitride semiconductor layer 554 may include a first typesemiconductor layer (not shown), an active layer (not shown), and asecond type semiconductor layer (not shown). The first typesemiconductor layer (not shown) may be a group III-N compoundsemiconductor layer doped with first type impurities, for example,n-type impurities, and may include, for example, an (Al, In, Ga)N groupIII nitride semiconductor, that is, an n-GaN layer.

The active layer (not shown) may be a group III-N semiconductor layer,for example, an (Al, Ga, In)N semiconductor layer. The active layer 134may be composed of a single layer or a plurality of layers, and emitlight having a certain wavelength. The active layer (not shown) may havea single quantum-well structure including one well layer (not shown), ora multi-quantum well structure wherein well layers (not shown) andbarrier layers (not shown) are alternately stacked one above another. Atthis time, each or both of the well layer (not shown) and the barrierlayer (not shown) may have a super-lattice structure.

The second type semiconductor layer (not shown) may be a group III-Ncompound semiconductor layer doped with second type impurities, forexample, p-type impurities, and may include, for example, an (Al, Ga,In)N group III nitride semiconductor, that is, a p-GaN layer.

The second nitride semiconductor layer 554 may further include asuper-lattice layer (not shown) or an electron blocking layer (notshown).

Then, a support substrate 570 is attached to the plurality of nitridesemiconductor layers 550.

The support substrate 570 may include a sapphire substrate, a GaNsubstrate, a glass substrate, a silicon carbide substrate or a siliconsubstrate; a conductive substrate formed of metallic materials; acircuit substrate such as a printed circuit board (PCB) or the like; anda ceramic substrate containing ceramic.

Although not shown in FIG. 29, a bonding layer (not shown) may bedisposed between the plurality of nitride semiconductor layers 550 andthe support substrate 570 to bond the plurality of nitride semiconductorlayers 550 to the support substrate 570.

Referring to FIG. 30, a process of separating the growth substrate 510from the nitride semiconductor layers 550 is performed.

In this embodiment, mechanical stress is applied to the sacrificiallayer 520 having the plurality of cavities 560 and breakage ispropagated along the cavities 560, whereby the sacrificial layer 520 canbe separated as shown in FIG. 5, thereby separating the supportsubstrate 570 from the growth substrate 510 and the nitridesemiconductor layers 550.

Referring to FIG. 31, a process of removing the insulation pattern 540from the support substrate 570 having the nitride semiconductor layers550 that has been separated from the growth substrate 510 is performed.

The sacrificial layer 520 may partially remain on the nitridesemiconductor layers 550, specifically on the nitride semiconductorlayers 550 and the insulation pattern 540, while the growth substrate510 is separated. Further, as shown in FIG. 6, a portion of thesacrificial layer 520 grown on the nitride semiconductor layers 550 canremain when the insulation pattern 540 is removed using the process ofremoving the insulation pattern 540.

As shown in FIG. 5 and FIG. 6, a first surface 526, which is a portionof a surface of the remaining sacrificial layer 520, may be a roughsurface. This is because the first surface 526 is formed when the innersurface of the cavities 560 or the surface of the sacrificial layer 520broken by propagation of breakage is exposed.

In addition, as shown in FIG. 6, the second surface 556, which is asurface of the first nitride semiconductor layer 552 exposed by removingthe insulation pattern 540, may be a rough surface. This is because thesecond surface 556 is exposed by removing the insulation pattern 540 andthus has a rough surface by the etching liquid for etching theinsulation pattern 540.

The first surface 526 and the second surface 556 may have differentroughness degrees. This is because the first surface 526 and the secondsurface 556 are formed in different layers and by different processes.

Referring to FIG. 32, the nitride semiconductor layers 550 on thesupport substrate 570 and a remaining portion of the sacrificial layer520 on the nitride semiconductor layers 550 are used to fabricate alight emitting diode by the method of separating a growth substrate froma nitride semiconductor layer according to the embodiment described withreference to FIG. 26 to FIG. 31.

That is, the light emitting diode may be fabricated by mesa etching theremaining portion of the sacrificial layer 520 and the nitridesemiconductor layers 550 such that a portion of the nitridesemiconductor layers 550, for example, a portion of the first typesemiconductor layer (not shown) of the second nitride semiconductorlayer 554 can be exposed; forming a first electrode 582 on a portion ofthe first type semiconductor layer (not shown) of the exposed secondnitride semiconductor layer 554 and a second electrode 584 on thenitride semiconductor layers 550; and dicing the support substrate 570to form individual light emitting diodes.

In the light emitting diode, the convex-concave pattern 586 is formed onthe surface of the nitride semiconductor layers 550 or on a portion ofthe surface of the remaining sacrificial layer 520 by the process ofseparating the growth substrate 510 or by the process of removing theinsulation pattern 540, and these surfaces are rough, whereby theuppermost surface of the nitride semiconductor layers 550 on the supportsubstrate 570 can have the convex-concave pattern 586 and rough surfaces526 and 556.

Thus, when light is extracted through the surface on the nitridesemiconductor layers 550, the light emitting diode has improved lightextraction efficiency.

The separated growth substrate 510 may be reused after a cleaningprocess for removing a portion of the sacrificial layer 520 remaining onthe surface thereof.

FIGS. 36 to 38 are a perspective view and cross-sectional views showinganother example of the light emitting diode including the nitridesemiconductor layer separated by the method of separating a growthsubstrate from a nitride semiconductor layer according to thisembodiment of the invention.

FIG. 36 is a cross-sectional view taken along line A-A′ of FIG. 37 andFIG. 38 is a cross-sectional view taken along line B-B′ of FIG. 37.

Referring to FIG. 36, the nitride semiconductor layers 550 on thesupport substrate 570 and a remaining portion of the sacrificial layer520 on the nitride semiconductor layers 550 are used to fabricate alight emitting diode by the method of separating a growth substrate froma nitride semiconductor layer according to this embodiment of theinvention described with reference to FIG. 26 to FIG. 31.

That is, an interlayer insulation film 542 is formed on the supportsubstrate 570 on which the nitride semiconductor layers 550 are formed.

The nitride semiconductor layers 550 may be divided into plural regions.The nitride semiconductor layers 550 may be divided by partially etchinga portion of the nitride semiconductor layers 550 through mesa etchingor the like to expose the support substrate 570.

In FIG. 36, side surfaces of the nitride semiconductor layers 550 areexposed by mesa etching and covered with the interlayer insulation film542. However, when the nitride semiconductor layers 550 are not divided,the interlayer insulation film 542 may be disposed in the form ofcovering the top of the nitride semiconductor layers 550.

The interlayer insulation film 542 may have an opening 544. The opening544 may be formed only in a region in which an electrode extension 588 bdescribed below will be formed.

The interlayer insulation film 542 may be provided to protect thenitride semiconductor layers 550 under the interlayer insulation film542, in particular, to protect the uppermost first nitride semiconductorlayer 552. Of course, the interlayer insulation film 542 may be omitted,as needed.

Referring to FIG. 37 and FIG. 38, an upper electrode portion 588 isformed on the support substrate 570 on which the interlayer insulationfilm 542 having the opening 544 is formed.

An upper electrode 588 a of the upper electrode portion 588 is formed onthe interlayer insulation film 542, and the electrode extension 588 b isformed within the opening 544 of the interlayer insulation film 542.

Therefore, the electrode extension 588 b is in direct contact with andelectrically connected to the first nitride semiconductor layer 552, andthe upper electrode 588 a is electrically connected to the first nitridesemiconductor layer 552 through the electrode extension 588 b withoutdirect contact.

At this time, the electrode extension 588 b may be formed in singular orin plural. That is, in this embodiment, two electrode extensions 588 bare formed, without being limited thereto. Alternatively, only oneelectrode extension or three or more electrode extensions 588 b may beprovided.

Then, the process of separating the support substrate 570 or the processof separating the nitride semiconductor layers 550 from the supportsubstrate 570 is performed, thereby providing a plurality of lightemitting diode chips, as shown in FIG. 37.

FIGS. 39 to 46 are cross-sectional views showing a method of separatinga growth substrate from a nitride semiconductor layer according to yetanother embodiment of the present invention.

FIG. 47 is a cross-sectional view of one example of a light emittingdiode including a nitride semiconductor layer separated by the method ofseparating a growth substrate from a nitride semiconductor layeraccording to this embodiment of the invention.

FIG. 48 is a conceptual view of examples of stripe patterns formed onone surface of a growth substrate.

Referring to FIG. 39, in the method of separating a growth substratefrom the nitride semiconductor layer according to this embodiment,first, a growth substrate 610 is prepared.

Then, a stripe pattern 612 is formed on one surface of the growthsubstrate 610.

The stripe pattern 612 may be formed by etching one surface of thegrowth substrate 610 to a predetermined depth and forming grooves eachhaving a bottom surface 612 a and an inclined surface 612 b.

The stripe pattern 612 may be formed by forming a mask pattern on onesurface of the growth substrate 610, followed by dry etching.

When the growth substrate 610 is a sapphire substrate, the stripepattern 612 is formed in a direction of 60 to 90 degrees with respect tothe sapphire substrate, as shown in (a) of FIG. 48 (i.e. in a directionof 90 degrees in (a) of FIG. 23).

In addition, when the growth substrate 610 is a GaN substrate, thestripe pattern 612 is formed in a direction of 60 degrees with respectto the GaN substrate, as shown in (b) of FIG. 48.

This is because portions of a sacrificial layer 620 are grown from thesurface of the growth substrate 610 at opposite sides of the stripepattern 612 when the sacrificial layer 620 is epitaxially grown on thegrowth substrate 610 having the stripe pattern 612 formed thereon, andthe portions of the grown sacrificial layer 620 are laterally grown andmerged into one layer to thereby form the sacrificial layer 620. Thatis, the sacrificial layers 620 are well merged when the stripe pattern612 is formed in the foregoing direction.

Then, a growth control layer 614 is formed on a bottom surface 612 a ofthe stripe pattern 612. When the sacrificial layer 620 is grown on thegrowth substrate 610, the sacrificial layer 620 may be grown on thebottom surface 612 a of the stripe pattern 612 instead of being grown onthe inclined surface 612 b of the stripe pattern 612. Thus, the growthcontrol layer 614 prevents growth of the sacrificial layer 620 on thebottom surface 612 a.

The growth control layer 614 may include an insulation material such assilicon oxide, silicon nitride, and the like.

Referring to FIG. 40, the sacrificial layer 620 is grown on the growthsubstrate 610 having the stripe pattern 612 formed thereon.

The sacrificial layer 620 is epitaxially grown after placing the growthsubstrate 610 into a chamber of an epitaxial growth system such as anMOCVD system. The sacrificial layer 620 may include GaN doped withimpurities, preferably n-GaN highly doped with n-type impurities.

When the sacrificial layer 620 is formed, growth conditions of thesacrificial layer 620, such as a flow rate of injected gas, growthtemperature, growth pressure, or the like, are controlled such that apartial surface 622 of the sacrificial layer 620 formed on the growthcontrol layer 614 can be uniform. When the partial surface 622 of thesacrificial layer 620 is not uniform while the sacrificial layer 620 islaterally grown, the sacrificial layer 620 can be non-uniformly etched,thereby making it difficult to separate the growth substrate 610.

In this embodiment, the growth control layer 614 serves to preventgrowth of the stripe pattern 612 on the bottom surface 612 a when thestripe pattern 612 is formed by dry etching. However, when the bottomsurface 612 a has a convex-concave pattern, or when the bottom surface612 a of the stripe pattern 612 is deep, there is no need to form thegrowth control layer 614.

In formation of the sacrificial layer 620, when the bottom surface 612 ahas a convex-concave pattern, growth does not occur on the bottomsurface 612 a. Further, when the bottom surface 612 a is deep, growthdoes not usually occur and does not affect sacrificial layer 620 evenwhen the growth occurs.

Referring to FIG. 41, a plurality of fine pores 631 is formed within thesacrificial layer 620.

The fine pores 631 may be formed to have the same shape as the finepores 531 including the first fine pores 532 and the second fine pores534 described with reference to FIG. 27, FIG. 33 and FIG. 34. Therefore,repetitive descriptions thereof will be omitted.

Referring to FIG. 42, an insulation pattern 640 is formed on thesacrificial layer 620.

The insulation pattern 640 may include an insulation material such assilicon oxide, silicon nitride, or the like.

The insulation pattern 640 may have open regions in the form of a stripeor mesh pattern.

Then, a plurality of nitride semiconductor layers 650 is formed on thesacrificial layer 620 having the insulation pattern 640 formed thereon.

The plurality of nitride semiconductor layers 650 may be formed throughregrowth by placing the growth substrate 610 again into the chamber ofthe epitaxial growth system such as an MOCVD system.

That is, the plurality of nitride semiconductor layers 650 may beepitaxially grown from the surface of the sacrificial layer 620 exposedthrough the open regions of the insulation pattern 640.

In this case, the fine pores 631 of the sacrificial layer 620 may form aplurality of cavities 660 when the plurality of nitride semiconductorlayers 650 are formed by epitaxial growth.

The plurality of cavities 660 may be formed by merging the plurality offine pores 531 into one, or by expanding one fine pore 631.

When the plurality of nitride semiconductor layers 650 is epitaxiallygrown, the size, position, number, or the like of cavities 660 may beadjusted by controlling the growth temperature for epitaxial growth, orthe kind and flow rate of injected gas.

The cavities 660 are generally formed in an upper region of thesacrificial layer 620 (here, the upper region of the sacrificial layer620 refers to a region close to an interface adjoining the plurality ofnitride semiconductor layers 650).

The cavities 660 may be formed to be larger in a distant region of thesacrificial layer 620 from the plurality of nitride semiconductor layers650 than a close region thereof, and may be formed to become larger withincreasing distance from the plurality of nitride semiconductor layers650.

FIG. 42 shows the nitride semiconductor layers 650 that include a firstnitride semiconductor layer 652 and a second nitride semiconductor layer654, without being limited thereto. Alternatively, the nitridesemiconductor layer may be composed of a single layer, or may becomposed of three or more layers.

The first nitride semiconductor layer 652 may be a buffer layer and thesecond nitride semiconductor layer 654 may be a semiconductor layerincluding at least an active layer.

That is, the first nitride semiconductor layer 652 may be an n-GaN layerdoped with n-type impurities or a μ-GaN layer doped with no impurity.

The second nitride semiconductor layer 654 may include a first typesemiconductor layer (not shown), an active layer (not shown) and asecond type semiconductor layer (not shown). In addition, the secondnitride semiconductor layer 654 may further include a super-latticelayer (not shown) or an electron blocking layer (not shown).

The first type semiconductor layer (not shown), the active layer (notshown), the second type semiconductor layer (not shown), thesuper-lattice layer (not shown) and the electron blocking layer (notshown) have been described in detail in the foregoing embodiments, andthus repetitive descriptions thereof will be omitted.

Referring to FIG. 43 and FIG. 44, mesa etching is performed with respectto at least the nitride semiconductor layer 650, thereby forming mesalines 670.

The mesa lines 670 serve to guide an etching liquid for etching thesacrificial layer 620 and are connected to at least the sacrificiallayer 620.

In this embodiment, since the stripe pattern 612 is formed on onesurface of the growth substrate 610, the mesa lines 670 may be connectedup to the cavities 660 and the stripe pattern 612 by etching the nitridesemiconductor layers 650 and the sacrificial layer 620.

Alternatively, when the stripe pattern 612 is not formed on the growthsubstrate 610, the mesa lines 670 may be provided so as to be connectedup to the cavities 660 of the sacrificial layer 620.

The mesa lines 670 may be formed throughout the growth substrate 610, asshown in FIG. 44.

That is, in a plan view of the growth substrate 610, the mesa lines 670may be formed from one end to the other end. The mesa lines 670 may bedisposed in the form of a stripe pattern repeatedly arranged on thegrowth substrate 610 in a vertical or horizontal direction.

In addition, the mesa lines 670 are repeatedly arranged on the growthsubstrate 610 in the vertical and horizontal directions such that thevertical mesa lines 670 and the horizontal mesa lines 670 intersect eachother to form a mesh pattern (see FIG. 19).

The mesa lines 670 may be formed to intersect the stripe pattern 612.That is, the direction of the mesa line 670 may be formed not to beparallel to the direction of the stripe pattern 612.

This configuration serves to connect more mesa lines 670 with the stripepattern 612, whereby the etching liquid injected through the mesa lines670 can be evenly injected to the surface of the growth substrate 610.

Referring to FIG. 45, a support substrate 680 is attached to theplurality of nitride semiconductor layers 650.

The support substrate 680 may include a sapphire substrate, a GaNsubstrate, a glass substrate, a silicon carbide substrate or a siliconsubstrate; a conductive substrate formed of metallic materials; acircuit substrate such as a printed circuit board (PCB) or the like; anda ceramic substrate containing ceramic.

Although not shown in FIG. 45, a bonding layer (not shown) may bedisposed between the plurality of nitride semiconductor layers 650 andthe support substrate 670 to bond the plurality of nitride semiconductorlayers 650 to the support substrate 670.

Then, a process of separating the growth substrate 610 from the nitridesemiconductor layers 650 is performed.

The separation process may be performed by injecting an etching liquidthrough the mesa lines 670 and etching the sacrificial layer 620.

The etching liquid is injected into the stripe pattern 612 through themesa lines 670, and thus a certain region 624 of the sacrificial layer620 placed on the stripe pattern 612 is first etched. At this time, thecertain region 624 of the sacrificial layer 620 to be etched may have atrapezoidal cross-section. Thus, when the insulation pattern 640 isformed, an open region may be properly determined in consideration ofthe trapezoidal etching region of the sacrificial layer 620.

At this time, the etching liquid may include NaOH and H₂O₂. The etchingliquid may include NaOH:H₂O₂:ultra-pure water in a ratio of 80:80:300(cc).

Etching is performed for 30 minutes at a temperature of 60 degrees,whereby the sacrificial layer 620 can be etched and separated. At thistime, the sacrificial layer 620 includes the cavities 660 and thus canbe more easily etched by the etching liquid.

The separation process may be modified. That is, etching may be finishedwithout completely separating the sacrificial layer 620 by a method ofshortening an etching time, and a process of applying mechanical stressto the sacrificial layer 620 may be additionally performed to separatethe growth substrate 610, thereby performing the separation process.

Referring to FIG. 46, a process of removing the insulation pattern 640is performed after separating the growth substrate 610 from the nitridesemiconductor layer 650.

When the insulation pattern 640 includes silicon oxide, buffered oxideetchant (BOE) may be used to remove the insulation pattern 640.

The surface of the nitride semiconductor layers 550 may be formed tohave a convex-concave pattern by removing the insulation pattern 640,and may become rough by the etching liquid for etching the sacrificiallayer 620, BOE for etching the insulation pattern 640, and the like.

After removing the insulation pattern 640, another process may beperformed by dipping the separated surface into a solution containingHCl, NaOH or a mixture of H₂SO₄ and H₂O₂ in order to remove a metallicmaterial, for example, metallic Ga.

FIG. 45 and FIG. 46 show the process of etching the sacrificial layer620 using the etching liquid and the process of removing the insulationpattern 640 by etching the insulation pattern 640 using BOE afterseparating the growth substrate 610. However, the insulation pattern 640may be etched through the stripe pattern 612 and the cavities 660 byinjecting BOE into the mesa line 670 instead of the etching liquid,whereby the support substrate 610 can be separated from the nitridesemiconductor layer 650 while removing the insulation pattern 640.

A third surface 656, which is a surface of the first nitridesemiconductor layer 652 exposed by etching the certain region 624 of thesacrificial layer 620 with the etching liquid, is formed to be rough, asshown in FIG. 21. The third surface 656 is formed by partially etchingthe surface of the first nitride semiconductor layer 652 by the etchingliquid.

In addition, a fourth surface 658, which is a surface of the firstnitride semiconductor layer 625 exposed by removing the insulationpattern 640, is formed to be rough, as shown in FIG. 21. The fourthsurface 658 is a surface exposed by removing the insulation pattern 640and thus has a rough surface by the etching liquid that etches theinsulation pattern 640.

The third surface 656 and the fourth surface 658 may have differentroughness degrees. This is because the third surface 656 and the fourthsurface 658 are formed by different processes.

Referring to FIG. 47, a light emitting diode is fabricated using thenitride semiconductor layers 650 formed on the support substrate 680 bythe method of separating a growth substrate from a nitride semiconductorlayer according to this embodiment of the invention described withreference to FIG. 39 to FIG. 46.

That is, the light emitting diode may be fabricated by mesa etching thenitride semiconductor layers 650 such that a portion of the nitridesemiconductor layers 650, for example, a portion of the first typesemiconductor layer (not shown) of the second nitride semiconductorlayer 654 can be exposed; forming a first electrode 692 on a portion ofthe first type semiconductor layer (not shown) of the exposed secondnitride semiconductor layer 554 and a second electrode 694 on thenitride semiconductor layers 650; and dicing the support substrate 680to form individual light emitting diodes.

In the light emitting diode, the surface of the nitride semiconductorlayer 650 is formed to have a convex-concave pattern 696 and to be roughby the process of separating the growth substrate 610 or by the processof removing the insulation pattern 640, whereby the uppermost surface ofthe nitride semiconductor layers 650 on the support substrate 680 canhave the convex-concave pattern 696 and rough surfaces 656, 258. Thus,when light is extracted through the uppermost surface of the nitridesemiconductor layers 650, the light emitting diode has improved lightextraction efficiency.

The separated growth substrate 610 may be reused after a cleaningprocess for removing a portion of the sacrificial layer 620 remaining onthe surface thereof.

FIGS. 49 to 51 are a perspective view and cross-sectional views showinganother example of the light emitting diode including the nitridesemiconductor layer separated by the method of separating a growthsubstrate from a nitride semiconductor layer according to thisembodiment of the invention.

FIG. 49 is a cross-sectional view taken along line A-A′ of FIG. 50 andFIG. 51 is a cross-sectional view taken along line B-B′ of FIG. 50.

Referring to FIG. 49, the nitride semiconductor layers 650 on thesupport substrate 680 are used to fabricate a light emitting diode bythe method of separating a growth substrate from a nitride semiconductorlayer according to the embodiment of the invention described withreference to FIG. 39 to FIG. 46.

That is, an interlayer insulation film 642 is formed on the supportsubstrate 680 on which the nitride semiconductor layers 650 are formed.

The nitride semiconductor layers 650 may be formed on the supportsubstrate 680 in a state of being divided into plural regions by themesa lines 670.

The interlayer insulation film 642 may have an opening 644. The opening644 may be formed only in a region where an electrode extension 698 bdescribed below will be formed.

The interlayer insulation film 642 may be provided to protect thenitride semiconductor layers 650 under the interlayer insulation film642, in particular, to protect the uppermost first nitride semiconductorlayer 652. Of course, the interlayer insulation film 642 may be omitted,as needed.

Referring to FIG. 50 and FIG. 51, an upper electrode portion 698 isformed on the support substrate 680 on which the interlayer insulationfilm 642 having the opening 644 is formed.

An upper electrode 698 a of the upper electrode portion 698 is formed onthe interlayer insulation film 642, and the electrode extension 698 b isformed within the opening 644 of the interlayer insulation film 642.

Therefore, the electrode extension 698 b is in direct contact with andelectrically connected to the first nitride semiconductor layer 652, andthe upper electrode 698 a is electrically connected to the first nitridesemiconductor layer 652 through the electrode extension 698 b withoutdirect contact.

At this time, singular or plural electrode extension 698 b may beformed. That is, in this embodiment, two electrode extensions 698 b areformed, without being limited thereto. Alternatively, only one electrodeextension or three or more electrode extensions 698 b may be provided.

Then, the process of separating the support substrate 680 is performed,thereby providing a plurality of light emitting diode chips, as shown inFIG. 25.

FIG. 52 is a cross-sectional view showing a method of separating agrowth substrate from a nitride semiconductor layer according to yetanother embodiment of the present invention.

Referring to FIG. 52, the method of separating a growth substrate from anitride semiconductor layer according to this embodiment is the same asthe separation method described with reference to FIG. 39 to FIG. 46,except that one surface of a growth substrate 610 is provided with astripe pattern 612′ having a different cross-section.

The stripe pattern 612′ substantially has a V-shaped cross-section, onesurface of which is less inclined to have a long inclined surface.

The stripe pattern 612′ may be formed by etching the growth substrate610 through wet-etching. That is, the stripe pattern 612′ may be formedby crystallographic characteristics of the growth substrate 610.

When the growth substrate 610 is a sapphire substrate having c-plane(0001) and is wet etched to form the stripe pattern 612′, other surfacesof the stripe pattern 612′ are exposed except for the c-plane, i.e.(0001) plane, on which the sacrificial layer 620 is grown.

As compared with the method of separating a growth substrate from anitride semiconductor layer described with reference to FIG. 39 to FIG.46, the c-plane of the inclined surfaces of the stripe pattern 612′according to this embodiment of the invention is not exposed and thusgrowth does not occur on the inclined surfaces of the stripe pattern612′. Therefore, the stripe pattern 612′ does not require the growthcontrol layer.

Accordingly, the method of separating a growth substrate from a nitridesemiconductor layer according to this embodiment of the inventionincludes the same process of growing the sacrificial layer 620 on thegrowth substrate 610 as the method of separating a growth substrate froma nitride semiconductor layer described with reference to FIGS. 39 and46, except that the stripe pattern 612′ is formed on one surface of thegrowth substrate 610. Therefore, repetitive descriptions thereof will beomitted.

FIGS. 53 to 58 are cross-sectional views showing a method of separatinga growth substrate from a nitride semiconductor layer according to yetanother embodiment of the present invention.

FIG. 59 is a cross-sectional view of one example of a light emittingdiode including a nitride semiconductor layer separated by the method ofseparating a growth substrate from a nitride semiconductor layeraccording to this embodiment of the invention.

Referring to FIG. 53, in the method of separating a growth substratefrom the nitride semiconductor layer according to this embodiment,first, a growth substrate 710 is prepared.

Then, a stripe pattern 712 is formed on one surface of the growthsubstrate 710.

The stripe pattern 712 may be formed by etching one surface of thegrowth substrate 710 to a predetermined depth and forming grooves eachhaving a bottom surface 712 a and an inclined surface 712 b.

The stripe pattern 712 may be formed by forming a mask pattern on onesurface of the growth substrate 710, followed by dry etching.

At this time, although not shown in FIG. 53, the stripe pattern 712 maybe replaced by the stripe pattern 612′ formed by wet etching describedwith reference to FIG. 27.

The stripe pattern 712 is the same as the stripe pattern 612 providedaccording to the foregoing embodiment of the invention, and thusrepetitive descriptions thereof will be omitted.

Then, a growth control layer 714 is formed on the bottom surface 712 aof the stripe pattern 712. The growth control layer 714 is the same asthe growth control layer 614 provided according to the foregoingembodiment of the invention, and thus repetitive descriptions thereofwill be omitted.

Then, a sacrificial layer 720 is grown on the growth substrate 710having the stripe pattern 712 formed thereon.

When the sacrificial layer 720 is formed, growth conditions of thesacrificial layer 620, such as a flow rate of injected gas, growthtemperature, growth pressure, or the like, are controlled such that apartial surface 722 of the sacrificial layer 720 formed on the growthcontrol layer 714 can be uniform. When the partial surface 722 of thesacrificial layer 720 is not uniform while the sacrificial layer 720 islaterally grown, the sacrificial layer 720 can be non-uniformly etched,thereby making it difficult to separate the growth substrate 710.

The sacrificial layer 720 is the same as the sacrificial layer 620described in the foregoing embodiment, and thus repetitive descriptionsthereof will be omitted.

Then, an insulation pattern 740 is formed on the sacrificial layer 720.

The insulation pattern 740 may serve to control the forming position ordirection of fine pores 731 while forming the fine pores 731, asdescribed below.

The insulation pattern 740 is formed to have a proper surface, therebyenabling good surface reformation of the nitride semiconductor layer 752formed on the insulation pattern 740.

The insulation pattern 740 may include an insulation material such assilicon oxide, or silicon nitride, etc.

The insulation pattern 740 may have open regions in the form of a stripeor mesh pattern.

Referring to FIG. 54, a plurality of fine pores 731 are formed withinthe sacrificial layer 720.

The fine pores 731 may be formed to a predetermined depth from thesurface of the sacrificial layer 720 exposed through the insulationpattern 740. That is, as shown in FIG. 29, the fine pores 731 may beformed not only under regions where the sacrificial layer 720 isexposed, but also under an edge of the insulation pattern 740.

This is because the fine pores 731 are formed not only in a directionperpendicular to the surface of the sacrificial layer 720 but also in adirection not perpendicular to the surface of the sacrificial layer 720,i.e. in an oblique direction.

The fine pores 731 may be formed to have the same shape as the finepores 531 including the first fine pores 532 and the second fine pores534 described with reference to FIG. 27, FIG. 34 and FIG. 35.

Therefore, repetitive descriptions of the process of forming the finepores 731 will be omitted.

Referring to FIG. 55, a plurality of nitride semiconductor layers 750are formed on the sacrificial layer 720 having the insulation pattern740 formed thereon.

The plurality of nitride semiconductor layers 750 may be formed throughregrowth by placing the growth substrate 710 again into the chamber ofthe epitaxial growth system such as an MOCVD system.

That is, the plurality of nitride semiconductor layers 750 may be grownfrom the surface of the sacrificial layer 720 exposed through the openregions of the insulation pattern 740.

In this case, the fine pores 731 of the sacrificial layer 720 may form aplurality of cavities 760 when the plurality of nitride semiconductorlayers 750 are grown.

The plurality of cavities 760 may be formed by merging the plurality offine pores 731 into one, or by expanding one fine pore 731.

When the plurality of nitride semiconductor layer 750 are epitaxiallygrown, the size, position, number, or the like of cavities 760 may beadjusted by controlling the growth temperature for epitaxial growth, orthe kind and flow rate of injected gas.

As shown in FIG. 55, the cavities 760 may be arranged substantially in aU shape throughout a certain region of the sacrificial layer 720 exposedthrough the insulation pattern 740 and a certain region of thesacrificial layer 720 under the edge of the insulation pattern 740. Thisis because the fine pores 731 are formed not only in a directionperpendicular to one surface of the sacrificial layer 720 but also in anoblique direction, and thus the cavities 760 are formed in a similarform.

FIG. 55 shows the nitride semiconductor layers 750 that include a firstnitride semiconductor layer 752 and a second nitride semiconductor layer754, without being limited thereto. Alternatively, the nitridesemiconductor layer may be composed of a single layer, or may becomposed of three or more layers.

The plurality of nitride semiconductor layers 750 including the firstnitride semiconductor layer 752 and the second nitride semiconductorlayer 754 according to this embodiment are the same as the plurality ofnitride semiconductor layers 650 including the first nitridesemiconductor layer 652 and the second nitride semiconductor layer 654provided according to the foregoing embodiment, and thus repetitivedescriptions thereof will be omitted.

Referring to FIG. 56, mesa etching is performed with respect to at leastthe nitride semiconductor layer 750, thereby forming mesa lines 770.

The mesa lines 770 serve to guide an etching liquid for etching thesacrificial layer 720 and are connected to at least the sacrificiallayer 620.

In this embodiment, the stripe pattern 712 is formed on one surface ofthe growth substrate 710, the mesa lines 770 may be connected up to thecavities 760 and the stripe pattern 712 by etching the nitridesemiconductor layers 750 and the sacrificial layer 720.

Alternatively, when the stripe pattern 712 is not formed on the growthsubstrate 710, the mesa lines 770 may be provided so as to be connectedup to the cavities 760 of the sacrificial layer 720.

The mesa line 770 is the same as the mesa line 670 provided according tothe foregoing embodiment, and thus repetitive descriptions thereof willbe omitted.

Then, a support substrate 780 is attached to the plurality of nitridesemiconductor layers 750.

The support substrate 780 may include a sapphire substrate, a GaNsubstrate, a glass substrate, a silicon carbide substrate or a siliconsubstrate; a conductive substrate formed of metallic materials; acircuit substrate such as a printed circuit board (PCB) or the like; anda ceramic substrate containing ceramic.

Although not shown in FIG. 56, a bonding layer (not shown) may bedisposed between the plurality of nitride semiconductor layers 750 andthe support substrate 780 to bond the plurality of nitride semiconductorlayers 750 to the support substrate 780.

Referring to FIG. 57, a process of separating the growth substrate 710from the nitride semiconductor layers 750 is performed.

The separation process may be formed by injecting an etching liquidthrough the mesa lines 770 and etching the sacrificial layer 720.

The etching liquid is injected into the stripe pattern 712 through themesa lines 770, and thus a certain region 724 of the sacrificial layer720 placed on the stripe pattern 712 is first etched. At this time, thecertain region 724 of the sacrificial layer 720 to be etched may have atrapezoidal cross-section. Thus, when the insulation pattern 740 isformed, an open region is properly formed in consideration of thetrapezoidal etching region of the sacrificial layer 720.

The process of separating the growth substrate 710 using the etchingliquid to etch the sacrificial layer 720 has been described in theforegoing embodiment in detail with reference to FIG. 45, and thusrepetitive descriptions thereof will be omitted.

Referring to FIG. 58, a process of removing the insulation pattern 740is performed after separating the growth substrate 710 from the nitridesemiconductor layer 750.

The process of removing the insulation pattern 740 and alternativeexamples of removing the sacrificial layer 720 and the insulationpattern 740 are described in detail in the foregoing embodiments withreference to FIG. 46, and thus repetitive descriptions thereof will beomitted.

After removing the insulation pattern 740, another process may beperformed by dipping the separated surface into a solution containingHCl, NaOH or a mixture of H₂SO₄ and H₂O₂ in order to remove a metallicmaterial, for example, metallic Ga.

A fifth surface 756, which is a surface of the first nitridesemiconductor layer 752 exposed by etching the certain region 724 of thesacrificial layer 720 with the etching liquid, is formed to be rough, asshown in FIG. 57. The fifth surface 756 is formed by partially etchingthe surface of the first nitride semiconductor layer 752 with theetching liquid.

In addition, a sixth surface 758, which is a surface of the firstnitride semiconductor layer 725 exposed by removing the insulationpattern 740, is formed to be rough, as shown in FIG. 58. The sixthsurface 758 is a surface exposed by removing the insulation pattern 740and thus has a rough surface by the etching liquid that etches theinsulation pattern 740.

The fifth source 756 and the sixth surface 758 may have differentroughness degrees. This is because the fifth surface 756 and the sixthsurface 758 are formed by different processes.

Referring to FIG. 59, a light emitting diode is fabricated using thenitride semiconductor layers 750 formed on the support substrate 780 bythe method of separating a growth substrate from a nitride semiconductorlayer according to this embodiment of the invention described withreference to FIG. 53 to FIG. 58.

That is, the light emitting diode may be fabricated by mesa etching thenitride semiconductor layers 750 such that a portion of the nitridesemiconductor layers 750, for example, a portion of the first typesemiconductor layer (not shown) of the second nitride semiconductorlayer 754 can be exposed; forming a first electrode 792 on a portion ofthe first type semiconductor layer (not shown) of the exposed secondnitride semiconductor layer 754 and a second electrode 794 on thenitride semiconductor layers 750; and dicing the support substrate 780to form individual light emitting diodes.

In the light emitting diode, the surface of the nitride semiconductorlayers 7350 is formed to have a convex-concave pattern 796 and to berough by the process of separating the growth substrate 710 or by theprocess of removing the insulation pattern 740, whereby the uppermostsurface of the nitride semiconductor layers 750 on the support substrate780 can have the convex-concave pattern 796 and rough surfaces 756 and358. Thus, when light is extracted through the surface on the nitridesemiconductor layers 750, the light emitting diode has improved lightextraction efficiency.

The separated growth substrate 710 may be reused after a cleaningprocess of removing a portion of the sacrificial layer 720 remaining onthe surface thereof.

FIGS. 60 to 62 are a perspective view and cross-sectional views showinganother example of the light emitting diode including the semiconductorlayer separated by the method of separating a growth substrate from anitride semiconductor layer according to this embodiment of theinvention.

At this time, FIG. 60 is a cross-sectional view taken along line A-A′ ofFIG. 61, and FIG. 62 is a cross-sectional view taken along line B-B′ ofFIG. 61.

Referring to FIG. 60, the nitride semiconductor layers 750 on thesupport substrate 780 are used to fabricate a light emitting diode bythe method of separating a growth substrate from a nitride semiconductorlayer according to this embodiment of the invention described withreference to FIG. 53 to FIG. 58.

That is, an interlayer insulation film 742 is formed on the supportsubstrate 780 on which the nitride semiconductor layers 750 are formed.

The nitride semiconductor layers 750 may be formed on the supportsubstrate 780 in a state of being divided into plural regions by themesa lines 770.

The interlayer insulation film 742 may have an opening 744. The opening744 may be formed only in a region where an electrode extension 698 bdescribed below will be formed.

The interlayer insulation film 742 may be provided to protect thenitride semiconductor layers 750 under the interlayer insulation film742, in particular, to protect the uppermost first nitride semiconductorlayer 752. Of course, the interlayer insulation film 742 may be omitted,as needed.

Referring to FIG. 61 and FIG. 62, an upper electrode portion 798 isformed on the support substrate 780 on which the interlayer insulationfilm 742 having the opening 744 is formed.

An upper electrode 798 a of the upper electrode portion 798 is formed onthe interlayer insulation film 742, and the electrode extension 798 b isformed within the opening 744 of the interlayer insulation film 742.

Therefore, the electrode extension 798 b is in direct contact with andelectrically connected to the first nitride semiconductor layer 752, andthe upper electrode 798 a is electrically connected to the first nitridesemiconductor layer 752 through the electrode extension 798 b withoutdirect contact.

At this time, singular or plural electrode extension 798 b may beformed. That is, in this embodiment, two electrode extensions 798 b areformed, without being limited thereto. Alternatively, only one electrodeextension or three or more electrode extensions 798 b may be provided.

Then, the process of separating the support substrate 780 is performed,thereby providing a plurality of light emitting diode chips, as shown inFIG. 36.

Although some embodiments have been described herein, it should beunderstood by those skilled in the art that these embodiments are givenby way of illustration only, and that various modifications, variations,and alterations can be made without departing from the spirit and scopeof the invention.

1. A semiconductor device comprising: a support substrate; and aplurality of semiconductor layers formed on the support substrate,wherein an uppermost layer of the semiconductor layers has a surfacewith non-uniform roughness.
 2. The semiconductor device according toclaim 1, wherein the surface of the uppermost layer comprises a cutsurface of the uppermost layer.
 3. The semiconductor device according toclaim 1, wherein the surface of the uppermost layer comprises an exposedinner surface of a cut void.
 4. The semiconductor device according toclaim 1, wherein the surface of the uppermost layer comprises aplurality of V-shaped etched grooves formed by an etching liquid foretching the uppermost layer.
 5. The semiconductor device according toclaim 1, wherein the uppermost layer comprises an open region exposinganother semiconductor layer under the uppermost layer.
 6. Thesemiconductor device according to claim 1, wherein the semiconductordevice comprises a light emitting diode, the semiconductor layerscomprise at least an active layer, and the uppermost layer comprises ann-type semiconductor layer.
 7. The semiconductor device according toclaim 1, wherein the uppermost layer among the semiconductor layerscomprises unmerged grooves on the surface thereof.
 8. The semiconductordevice according to claim 1, wherein the uppermost layer among thesemiconductor layers comprises a convex-concave pattern and a roughsurface.
 9. The semiconductor device according to claim 8, wherein therough surface comprises two surfaces having different roughness degrees.10. The semiconductor device according to claim 8, wherein one of thetwo surfaces having different roughness degrees has the convex-concavepattern.
 11. The semiconductor device according to claim 8, wherein oneof the two surfaces having different roughness degrees comprises asurface formed by breaking a layer comprising cavities.
 12. A method ofseparating a growth substrate from an epitaxial layer, comprising:preparing a growth substrate; forming a convex-concave patterncomprising a plurality of convex portions and concave portions on onesurface of the growth substrate; epitaxially growing a sacrificial layeron the convex portions of the convex-concave pattern; forming aplurality of fine pores by performing electro chemical etching (ECE) onthe sacrificial layer; epitaxially growing a plurality of semiconductorlayers on the sacrificial layer; attaching a support substrate to thesemiconductor layers; and separating the growth substrate, wherein aplurality of voids are formed by merging or growing the fine poreswithin the sacrificial layer after the semiconductor layers areepitaxially grown on the sacrificial layer.
 13. The method according toclaim 12, further comprising: forming a growth control layer on theconcave portions of the convex-concave pattern before epitaxial growthof the sacrificial layer.
 14. The method according to claim 12, whereinthe concave portions comprise trapezoidal grooves, a cross-section ofwhich has a narrow bottom side and a wide top side.
 15. The methodaccording to claim 12, wherein the concave portions have a V-shapedcross-section.
 16. The method according to claim 12, wherein epitaxiallygrowing of the sacrificial layer comprises epitaxially growing thesacrificial layer from each of the convex portions.
 17. The methodaccording to claim 12, wherein separating the growth substrate comprisesapplying stress to the sacrificial layer.
 18. The method according toclaim 12, wherein separating the growth substrate comprises injecting anetching liquid for etching the sacrificial layer into the concaveportions of the convex-concave pattern.
 19. A method of separating agrowth substrate from an epitaxial layer, comprising: preparing a growthsubstrate; forming a convex-concave pattern comprising a plurality ofconvex portions and concave portions on one surface of the growthsubstrate; epitaxially growing a sacrificial layer on the convexportions of the convex-concave pattern; forming a mask pattern on thesacrificial layer such that open regions can be formed corresponding tothe concave portions of the convex-concave pattern; epitaxially growinga plurality of semiconductor layers over the mask pattern from thesacrificial layer exposed through the open regions; etching at least aportion of the sacrificial layer exposed through the concave portionsand a portion of the semiconductor layer formed in the open regions ofthe mask pattern by injecting an etching liquid for etching thesacrificial layer into the concave portions of the convex-concavepattern; and separating the semiconductor layers from the growthsubstrate.
 20. The method according to claim 19, further comprising:forming a growth control layer on the concave portions of theconvex-concave pattern before epitaxial growth of the sacrificial layer.21. The method according to claim 19, further comprising: attaching asupport substrate to the semiconductor layers before separating thesemiconductor layers.
 22. The method according to claim 19, whereinseparating the semiconductor layers from the growth substrate comprisesetching the mask pattern by injecting an etching liquid for etching themask pattern into the concave portions of the convex-concave pattern.23. The method according to claim 19, wherein the concave portionscomprise trapezoidal grooves, a cross-section of which has a narrowbottom side and a wide top side.
 24. The method according to claim 19,wherein the concave portions have a V-shaped cross-section.
 25. Themethod according to claim 19, wherein epitaxially growing of thesacrificial layer comprises epitaxially growing the sacrificial layerfrom each of the convex portions.
 26. A method of separating a growthsubstrate from an epitaxial layer, comprising: preparing a growthsubstrate; growing a sacrificial layer on one surface of the growthsubstrate; forming a plurality of fine pores within the sacrificiallayer; forming a plurality of cavities from the plurality of fine pores;and separating the growth substrate using the plurality of cavities. 27.The method according to claim 26, further comprising: forming aninsulation pattern on a surface of the sacrificial layer before or afterforming the plurality of fine pores.
 28. The method according to claim26, wherein forming the plurality of cavities from the plurality of finepores comprises: growing a plurality of nitride semiconductor layers onthe sacrificial layer; and forming the plurality of cavities from theplurality of fine pores while growing the nitride semiconductor layers.29. The method according to claim 26, wherein preparing the growthsubstrate comprises forming a stripe pattern on one surface of thegrowth substrate.
 30. The method according to claim 29, wherein thestripe pattern is formed by etching one surface of the growth substratethrough dry etching or wet etching.
 31. The method according to claim30, wherein the forming the stripe pattern comprises forming a growthcontrol layer on a bottom surface of the stripe pattern after the stripepattern is formed on one surface of the growth substrate by dry etchingone surface of the growth substrate.
 32. The method according to claim29, wherein, when the growth substrate is a sapphire substrate, thestripe pattern is formed in a direction from 60 to 90 degrees withrespect to the sapphire substrate, and when the growth substrate is aGaN substrate, the stripe pattern is formed in a direction of 60 degreeswith respect to the GaN substrate.
 33. The method according to claim 26,wherein the sacrificial layer comprises n-GaN.
 34. The method accordingto claim 33, wherein the sacrificial layer comprises at least two layershaving different concentrations of n-type impurities.
 35. The methodaccording to claim 26, wherein the plurality of fine pores are formed byelectro chemical etching (ECE).
 36. The method according to claim 35,wherein the plurality of fine pores are formed by applying voltages ofat least two levels, and voltage applied initially has a lower levelthan voltage applied later.
 37. The method according to claim 26,wherein separating the growth substrate using the plurality of cavitiescomprises: forming nitride semiconductor layers on the sacrificiallayer; attaching the support substrate to the nitride semiconductorlayers; and separating the growth substrate and the nitridesemiconductor layers by applying mechanical stress to the sacrificiallayer.
 38. The method according to claim 26, wherein separating thegrowth substrate using the plurality of cavities comprises: formingnitride semiconductor layers on the sacrificial layer; forming a mesaline connected to at least the cavities by mesa etching the nitridesemiconductor layers and the sacrificial layer; attaching the supportsubstrate to the nitride semiconductor layers; and separating the growthsubstrate from the nitride semiconductor layers by injecting an etchingliquid into the mesa line to etch the sacrificial layer.
 39. The methodaccording to claim 38, wherein the growth substrate comprises a stripepattern on one surface thereof and the mesa line is connected to thestripe pattern.
 40. The method according to claim 39, wherein the mesaline is formed so as not to be parallel to the stripe pattern such thatthe mesa line and the stripe pattern intersect each other.
 41. Themethod according to claim 37, further comprising: removing theinsulation pattern after separating the growth substrate from thenitride semiconductor layers.
 42. The method according to claim 38,further comprising: removing the insulation pattern after separating thegrowth substrate from the nitride semiconductor layers.